New Geochronological Constraints on the Late Palaeozoic Tarija Basin, Southern Bolivia: Tectonic and Palaeoclimatic Implications

Abstract

The Carboniferous-Permian Tarija basin of southern Bolivia evolved under major tectonic and climatic influence. The timing of transition from glacially influenced to arid conditions, after the Gondwanide tectonic event, has been based mainly on palynological correlations. This study presents data from three U–Pb detrital zircon samples (~500 grains each), providing two robust maximum deposition ages (327±4 and 259±3Ma). These results are integrated with stratigraphic cycles defining the Macharetí, Mandiyutí and Cuevo Groups. Our interpretation, supported by our data and previous studies, constrains a Mississippian to earliest Pennsylvanian age for the Macharetí Group and a Pennsylvanian age for the later Mandiyutí Group, both bounded by the regional Intra-Carboniferous unconformity (~318Ma). A major depositional hiatus followed the end of glaciation, with arid sedimentation recorded only after the late Permian (Cuevo Group).